Arm



FIG. 1 is a left front perspective view of an arm showing my new design;

FIG. 2 is a right front perspective view, thereof;

FIG. 3 is a left side elevational view

FIG. 4 is a rear elevational view thereof; and,

FIG. 5 is a top view thereof.

The views of the arm not shown form no part of the claimed design. The dashed lines represent environmental elements only and form no part of the claimed design. 

The ornamental design for an arm, as shown and described. 